Fractal Structure and Deformation of Fractured Rock Masses
A numerical simulation method is used to predict connectivity of fractured rock masses. Hiere is a threshold of fracture density, below which fractures are poorly connected. Where fracture density is at or above the threshold, there is a continuous fracture cluster (i.e. the largest cluster) throughout the fractured rock mass. Fractal dimension, Df, is used to describe quantitatively the connectivity and compactness of the largest fracture cluster in the fractured rock mass and increases with fracture density. The critical fractal dimension, Dfc, describes the geometry of the largest fracture cluster at the threshold of fracture density, and has a rather constant value of 1.22 to 1.38 for wide variations in the distribution of size and orientations of the fractures.
Simulation of biaxial compressive tests of fractured rock masses has been carried out using a numerical method, UDEC (Universal Distinct Element Code). The deformation of fractured rocks increases greatly with fractal dimension and is mainly created by the shear displacements and openings along fractures. A link between fracture density and deformability of a fractured rock mass is established through the fractal dimension.
KeywordsPermeability Sandstone Excavation
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